Our mySQL install kept giving us trouble, even though the install went fine, after restarts the mySQL database would not be available.
What fixed it? We changed ~/Library/LaunchDaemons/com.mysql.mysql.plist to this:
<?xml version=”1.0″ encoding=”UTF-8″?>
<!DOCTYPE plist PUBLIC “-//Apple//DTD PLIST 1.0//EN” “http://www.apple.com/DTDs/PropertyList-1.0.dtd”>
<plist version=”1.0″>
<dict>
<key>KeepAlive</key>
<true/>
<key>Label</key>
<string>com.mysql.mysqld</string>
<key>Program</key>
<string>/usr/local/mysql/bin/mysqld_safe</string>
<key>RunAtLoad</key>
<true/>
<key>UserName</key>
<string>_mysql</string>
<key>WorkingDirectory</key>
<string>/usr/local/mysql</string>
<key>ExitTimeOut</key>
<integer>1</integer>
</dict>
</plist>
Bingo, back in business!